Write the formula for Lithium Nitride.
Agenda for Tuesday Jan 11th 1.Review/Practice Ionic Bonds2.Metallic Bonds3.Covalent bonds
Rules for writing Ionic formulas
1. The metal comes first (this does not include hydrogen), non-metal comes second.
2. Find the oxidation number of each element3. The oxidation number of the metal becomes
the subscript number of the non-metal and vise versa.
Lithium nitride:Li1+ and N3- Li3N1 or Li3N
Rules for Naming Ionic formulas
1. Write the name of the positive ion (metal).2. If you have a transition metal then you need to
figure out its charge (remember the compound’s oxidation numbers must equal 0) and put it in roman numerals after the name; e.g. Copper (II). If it is not a transition metal proceed to step 3.
3. Write the root of the non-metal’s name (chlor- for chlorine, ox- for oxygen).
4. Add the ending –ide to the root.
Metallic Bonding
• Composed of closely packed cations• Valence e- are a “sea of electrons”• Attraction between valence e- and cations
Metallic Bonding
• “sea of electrons” model explains physical properties of metals
– Good conductors – e- flow freely– Ductile– malleable– luster
Covalent Bonding
• Nonmetal + nonmetal• share electrons– Can share more than one pair
(double, triple bond)
• Atoms held together by sharing electrons are covalently bonded
Covalent (Molecular) Bonds
• Properties– Molecules– Lower melting and boiling points– Most are liq or gas– Nonconductors– Start to talk about shapes of molecules
Ammonia molecule
Multiple Bonds
• Double and triple covalent bonds– Sharing more than one pair of e-
Carbon dioxideNitrogen
• Triple bonds are stronger than double bonds– More energy needed to break 3 bonds than 2 bonds
Polar and Nonpolar
• Covalent bonding can be:
a) Polar – electrons not shared equallyb) Nonpolar – electrons shared equally
Drawing Covalent Compounds
• Draw Dot structure for each compound• Pair unpaired electrons of each compound• Draw a line where you paired electrons
Prefixes
Number of atoms
Prefix Number of atoms
Prefix
1 Mono 6 Hexa
2 Di 7 Hepta
3 Tri 8 Octa
4 Tetra 9 Nona
5 Penta 10 Deca
Naming Covalent Compounds
• 1st word: Give the prefix designating the number of atoms of the first element present, then write the element’s name.
• 2nd word: Give the prefix designating the number of atoms of the second element present.
• CO2: carbon di• Name the root of the second element.
• CO2: carbon diox• Add –ide to the root of the second element.
• CO2: carbon dioxide (official name)
Practice
• N2O4
• PCl5
• NO
• CCl4• SCl2
• Dinitrogen Tetroxide• Phosphorus Pentachloride• nitrogen monoxide –or nitrogen oxide
• Carbon Tetrachloride• Sulfur Dichloride
More Practice
• Sulfur Hexafluoride • Pentanitrogen
Heptoxide• Diodine tetrachloride• Triastatine Octoxide• Phosphorous
Mononitride
• SF6
• N5O7
• I2Cl4• At3O8
• PN
Bonding
100% ionic 100% covalent polar covalent ionic and covalent
NaCl NaNO3 Cl2
KBr Br2